As is known in the art, a colonoscopy refers to a medical procedure for examining a colon to detect abnormalities such as polyps, tumors or inflammatory processes in the anatomy of the colon. The colonoscopy is a procedure which consists of a direct endoscopic examination of the colon with a flexible tubular structure known as a colonoscope which has fiber optic or video recording capabilities at one end thereof. The colonoscope is inserted through the patient's anus and directed along the length of the colon, thereby permitting direct endoscopic visualization of colon polyps and tumors and in some cases, providing a capability for endoscopic biopsy and polyp removal. Although colonoscopy provides a precise means of colon examination, it is time-consuming, expensive to perform, and requires great care and skill by the examiner. And, the procedure also requires thorough patient preparation including ingestion of purgatives and enemas, and usually a moderate anesthesia. Moreover, since colonoscopy is an invasive procedure, there is a significant risk of injury to the colon and the possibility of colon perforation and peritonitis, which can be fatal.
To overcome these drawbacks, the virtual colonoscopy was conceived. A virtual colonoscopy makes use of images generated by computed tomography (CT) imaging systems (also referred to as computer assisted tomography (CAT) imaging systems). In a CT (or CAT) imaging system, a computer is used to produce an image of cross-sections of regions of the human body by using measure attenuation of X-rays through a cross-section of the body. In a virtual colonoscopy, the CT imaging system generates two-dimensional images of the inside of an intestine. A series of such two-dimensional images can be combined to provide a three-dimensional image of the colon. While this approach does not require insertion of an endoscope into a patient and thus avoids the risk of injury to the colon and the possibility of colon perforation and peritonitis, the approach still requires thorough patient preparation including purgatives and enemas. Generally, the patient must stop eating and purge the bowel by ingesting (typically by drinking) a relatively large amount of a purgative. Another problem with the virtual colonoscopy approach is that, the accuracy of examinations and diagnosis using virtual colonoscopy techniques is not as accurate as is desired. This is due, at least in part, to the relatively large number of images the examiner (e.g. a doctor) must examine to determine if a polyp, tumor or an abnormality exists in the colon.
It would, therefore, be desirable to provide a virtual colonoscopy technique which removes the need for bowel cleansing. It would also be desirable to provide a virtual colonoscopy technique which removes the need for thorough patient preparation.
It would further be desirable to provide a technique which increases the accuracy of examinations and diagnosis using virtual colonoscopy. It would be further desirable to provide a technique which reduces the number of images an examiner (e.g. a doctor) must examine to determine if a polyp, tumor or an abnormality exists in the colon. It would be further desirable to provide a technique for automatic detection of polyps, tumors or other abnormalities in the colon.